This invention relates in general to a telephone cable, and in particular to a cable having at least one basic bundle of conductors assembled of at least three component conductors formed respectively of SZ-stranded pairs or quads of wires.
SZ type of stranding means that individual wires are alternately laid clockwise and counterclockwise with twist-free transition zones therebetween. By using the SZ stranding of pairs of quads of wires, a communication cable consisting of one or more basic bundles can be manufactured in a continuous working process starting from individual wires until the completed assembly of basic bundles or a single bundle is provided, if desired, with a protecting jacket. The individual SZ pairs or SZ quads are stranded into the bundle, for example by means of a rotary winder. The assembled pairs or quads of SZ stranded wires in respective basic bundles are laid in such a manner that the transitions from the S-like to the Z-like twist or lay, and vice versa, are shifted in phase relative to each other and/or the individual SZ pairs or quads are stranded with different lengths of lay or twist in order to achieve an improvement of transmission quality of the cable by electrically uncoupling the adjoining strands. It has been found, however, that in prior-art basic bundles of component conductors produced by the above described methods, the capacitive couplings K.sub.9 to K.sub.12 have not been reduced to a sufficient level due to the fact that transition areas in which the wires extend parallel to each other between respective S and Z lays, and vice versa, overlap each other in the individual SZ pairs or quads. To remove this shortcoming, attempts have been made to shorten these interfering parallel areas so that the probability of overlapping be reduced to a minimum. To achieve such short transition zones, however, necessitates the application of costly SZ stranding machines without achieving a really substantial improvement.